What is Silica Brick?

First of all, the most basic is the nature of common silica brick belongs to the acidity.
The true density of silica brick is smaller, the lime translation is more complete, in the process of the oven and residual expansion is smaller. In silica brick, the true density of the quartz crystal is  smallest, linear expansion rate is small, the thermal stability is better than cristobalite and quartz, thermal conductivity is good, refractoriness under load is high, slag corrosion resistance is strong, is the most stable form quartz in volume. In better firing silica brick, the content of scale quartz is the highest, accounted for 50% ~ 80%, cristobalite times, only 10% ~ 30%, the content fluctuation of quartz and glass phase is in 5% ~ 15%.
When working temperature is below 600 ~ 700 ℃, silica brick volume change is bigger, the resistance to thermal shock performance is poorer, thermal stability is not good. If coke oven is in long-term work under this kind of temperature, masonry is easily broken.





The key to determine whether thermal stability is good is true density, the size of true density is to determine one of the important marks of the quartz translation.
Silica brick belongs to the acid refractory material, with good acid erosion resistance, its thermal performance is good, refractoriness under load is high, generally is above 1620 ℃, the refractoriness is only lower 70 ~ 80 ℃ . The thermal conductivity of silica brick increases with the rising of temperature, no residual shrinkage, in the process of oven, the volume of a silica brick increases as the temperature increases. So, silica brick is the ideal refractory products of coke oven, the maximum expansion of silica brick occurs in 100 ~ 300 ℃, the expansion before 300 ℃ is about 70% ~ 75% of total amount of expansion. The reason for this is that  SiO2 is in the process of oven, appeared four crystal shape transformation of 117 ℃,  163 ℃ and 180 ~ 270 ℃ and 573 ℃, of which 180 ~ 270 ℃, caused by the volume expansion of cristobalite is maximum.